So, if you're in the weight room and you notice someone doing an exercise with absolutely terrible form so that they're either not working the muscle they think they're working at all or they're puting themselves in a position to greatly damage themselves do you tell them?

Couple of examples:
yesterday there were a couple of guys next to me dead lifting, one of them was a fairly experienced lifter, decent form on his DL and he was working with an obvious beginner who's DL form was attrocious (complete rounding of the back, complete lift with the back). Every time he did a rep I winced because I was just waiting for his spine to die.

Today I was watching a guy who probably thought he was on bicep day but from the amount of swing in his curls (both dumbell and barbell) he most certainly was getting a good back workout.

if the form is poor for an exrx such as deadlift or squat then i would suggest proper form once that set was done but for anything else really i just keep to myself.
if someone asks for a spot or for form then i will say something as well
i see lots of guys using too much to impress other members and think they are tough so i just let them do there thing.
as long as my form for certain exrx is correct i dont mind others.

I don't comment on poor form by other lifters in my health club, since that's the job of the personal trainers. Most of the poor form that I see is cheating in order to lift a weight that can't be lifted cleanly, like Eric pointed out earlier.

Most gyms usually have paid fitness advisors/instructors walking around to make sure everyone is being safe and following the rules of the gym.

Especially at the YMCA where I go to, there are at least 3 of them always correcting everyone on their form and asking anyone of they need a spotter, etc. Many people at the gym often go to them for help on a particular exercise.

Well I corrected someone on his bent over row form yesterday, only to find out that he thinks his personal trainer told him to use too much weight, so he had to cheat to do it. (instead of lower the weight)

In general I try to correct someone's form when it doesn't look good for their back, everything else I just ignore.

About 2 weeks ago, I saw a personal trainer with a client, they were doing bent over rows with a very rounded back, and jerking the weight. Another client was doing squats (same personal trainer) and their knees were going beyond their toes...

Also, every time I see a Personal Trainer give their clients squats, they never go deep, and they don't even go parallel, they seem to do quarter reps...

KPj wrote:About 2 weeks ago, I saw a personal trainer with a client, they were doing bent over rows with a very rounded back, and jerking the weight. Another client was doing squats (same personal trainer) and their knees were going beyond their toes...

Also, every time I see a Personal Trainer give their clients squats, they never go deep, and they don't even go parallel, they seem to do quarter reps...

I guess you are fighting a losing battle with the form thing....

KP

Just to be clear, I think knees are allowed to move over in front of toes.